Attack Rate (AT)

Attack rates are actually risks (or "incidence proportion" or "cumulative incidence"). Attack rates are often expressed as a percentage. An attack rate is not an incidence rate. It is actually a risk (also called incidence proportions), and the time contribution of each individual is not included in the denominator. The denominator consists of the number of individuals present at the beginning of the outbreak, disregarding those who will leave, develop illness, or die. This means that the cases (numerator) are also included in the denominator: it is therefor a true proportion. In outbreaks of short duration, attack rate is a term frequently used instead of risk or incidence proportion. In a foodborne outbreak, we will often refer to "food specific attack rates". In this circumstance, the denominator will consist of the number of individuals who ate a specific food, while the numerator will consists of the number of individuals who ate that food and became ill.

Data and Resources
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PublicationTitle Attack rates and case fatality
PublicationType Website
PublicationYear Accessed: 16.05.2019
Publisher European Centre for Disease Prevention and Control (ECDC)
Glossary Term Classification
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Category Epidemiology
ModifiedDefinition true
RelatedTerm incidence rate
Sector Public Health
Additional Info
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Provided by: EJP ORION project
system:type GlossaryTerm
Management Info
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Author taras_guenther
Last Updated 28 April 2020, 01:33 (CEST)
Created 26 September 2019, 13:00 (CEST)